FIG. 7 is a perspective view of a general stator yoke in one type of resolver.
A stator yoke 101 includes an outside cylindrical part 102, a winding part 103 facing toward the center from the cylindrical part 102, and a winding holding part 104 provided in a protruding condition at the tip of the winding part 103. A combination of the winding part 103 and the winding holding part 104 is called a tooth 105.
The winding holding part 104 is formed into a rectangular parallelpiped having a quadrate inward surface. The width of a protrusion 107 of a residual obtained by subtracting the width of the winding part 103 from the width of the winding holding part 104 in the circumferential direction is twice as large as a width L1 of a one-sided protrusion 106. Besides, the height of the stator yoke 101 in the center axis direction (direction of the center axis of the outside cylindrical part 102 of the stator yoke 101) is uniformly formed to be H1. The height of the one-sided protrusion 106 is also H1.
In the stator yoke 101 of FIG. 7, a winding (not shown) with insulating coating is wound around the winding part 103 through an insulator (not shown). The illustration of a rotor is omitted. As shown in FIG. 7, a resolver including one stator yoke 101 in which a number of teeth 105 are provided on one cylindrical part 102 and windings are wound around the teeth 105, and one rotor (not shown) is called a simplexed resolver. A multiplexed resolver, for example, an M-plexed resolver is such that basically, the resolver of FIG. 7 is made one resolver unit and M such resolver units are assembled and fixed.
As an insulator provided on the winding part 103, a slot insulator is used.
A pair of slot insulators are mounted (attached) to the stator yoke 101 of FIG. 7 so as to cover the stator yoke 101 from above and below in a direction along the center axis of the stator yoke 101 (see, for example, JP-A-2001-95188, JP-A-2001-169493 and JP-A-2002-171737).
In the case where the slot insulator is used, as compared with a case where a surface of a stator yoke is directly subject to insulating coating, and the winding is provided thereon, there are following merits. Thus, the slot insulator plays an important role at the time of mass production.
(1) In the case of the slot insulator, only a step of direct attachment to the stator yoke is used. On the other hand, in the case where the surface of the stator yoke is subjected to insulating coating, it is necessary to perform plural steps, such as a step of subjecting the stator yoke to the insulating coating and a step of drying it thereafter. Thus, in the case where the slot insulator is used, since the number of insulating process steps of the stator yoke becomes small, the assembling process is short, and manufacturing cost becomes low.
(2) Since the slot insulator is molded out of resin by a metal mold, the unit cost is low.
(3) In the case where an insulating coating material is applied, a gap such as a pinhole is produced in the coating due to uneven coating or the like. On the other hand, since the slot insulator is molded by injecting resin into the metal mold under high pressure, a gap such as a pinhole is not easily produced in the molded resin. Thus, in the slot insulator, insulation between the stator yoke and the coil is more easily ensured.
(4) In the case where an insulating coating material is applied, since the coating material is merely applied to an existing part, the structure can not be changed. On the other hand, since the slot insulator is molded out of resin, the shape and structure of a crossover guide, a winding protection part, a connector, a cover and the like can be freely designed and changed.
Incidentally, as the resolver, in addition to the above structure, a multiplexed (M-plexed) resolver in which plural (arbitrary M) resolver units are stacked into an integral assembly is known.
Also in the multiplexed resolver, although it has been examined to similarly use the slot insulator, this has not been realized.
Hereinafter, for reference, a structure relating to a slot insulator, which was attempted to be adopted for the multiplexed resolver and was not be realized, will be described.
FIG. 8 is a perspective view of a stator yoke in a duplexed resolver.
A stator yoke 1 of the duplexed resolver of FIG. 8 is the stator yoke of the duplexed resolver in which a structure of a simplexed resolver is made one resolver unit, and two such resolver units are stacked to form an integral assembly.
Winding parts 3 are provided on each of the upper and lower stator yokes 1 to be shifted so that they are not overlapped with each other at a common angle position on the circumference. A winding holding part 4 and the winding part 3 constitute a tooth 5.
The number of the teeth 5 and the interval are suitably set in relation to an axial double angle or the like. However, it is preferable that the arrangement of the respective teeth 5 in the circumferential direction is the arrangement in the order corresponding to the order of the resolver units, that is, the stator yokes.
An interval of a height H3 equivalent to the thickness of a cylindrical part 2 is produced between the winding parts 3 of the upper and lower stator yokes 1.
Although the above is an example of the duplexed resolver, the form of a triplexed or higher multiplexed resolver can be similarly constructed.